1. Field of the Invention
The present invention relates to time keeping devices, and more particularly, to a time-keeping correction apparatus for correcting time in a slave time-keeper in accordance with a master time-keeper.
2. Description of the Prior Art
Many organizations, such as schools, businesses, hospitals and other facilities where occupants wish to be uniformly informed of correct time for scheduling purposes, install and operate multiple clocks that all display a same time. Unfortunately, the time displayed on these clocks often deviates because of such events as a general or local power interruption, daylight savings time adjustments, or clock malfunctioning.
To compensate for these deviations so as to synchronize displays of all clocks in a facility, many organizations install self adjusting clock systems including a "master" clock that keeps the correct time and a plurality of individual "slave" clocks located throughout the facility. The master clock provides a control signal to the slave clocks to correct for any deviations in the displayed times.
Prior art self-adjusting clock systems suffer from several drawbacks. For example, analog slave clocks have previously been designed to only provide one method of correction. However, several correction methods exist to correct the time on slave clocks connected to the master clock. This makes it difficult to replace one or more of the slave clocks, because a slave clock would have to be found that provided the particular method of correction used by the master clock.
Prior art self adjusting clock systems are also inaccurate. In some traditional master/slave clock methods, the master clock sends a correction pulse to the slave clocks. After receiving the correction pulse or pulses, the slave clocks advance to a predetermined position based on the correction signal until they strike a mechanical stop. This method does not account for time that lapses while the hands are moved to the new position. Therefore, the time shown on the slave clocks is inaccurate even after the correction sequence.
Prior art self-adjusting clock systems also cannot "remember" the position of the hands during a power outage. By lacking capability of retaining such positional information, previous systems have relied on various sensors to determine the position of hands or have used a system of mechanical stops to establish hand positions.
Additionally, existing self-adjusting clock systems lack local fast forwarding capabilities for their analog slave clocks. This is not desirable as a user may wish to fast forward the position of the hands of a particular clock to a chosen time.